It is known to provide a shutter having at least two shutter sectors which are swingably mounted upon a support and are adapted to block a shutter opening upon swinging movement in one direction and to expose this opening or permit light to pass therethrough upon swinging movement in an opposite direction.
Shutters of this type have been provided with rectilineally shiftable elements to actuate the shutter sectors (two in number). In an alternative conventional construction, a multiplicity (more than two) sectors are provided for actuation by a control ring which is concentric with the opening and is rotated to swing the sectors between their extreme positions.
Both of these conventional systems have the disadvantage that the individual sectors have a relatively high inertia and thus limit the shutter speed. The concentric-ring structure is, in addition, a complicated mechanism capable of failure and of poor reliability. High friction losses also arise in the earlier systems.